PLACE CHOCOLATE IN a large microwave-safe bowl and melt on medium-low, about 2 minutes.
Whisk in oil and coffee and blend until smooth. Set aside.
IN A LARGE bowl with an electric mixer, beat egg whites and cream of tartar on medium speed. Gradually add sugar and continue beating until you have soft peaks.
FOLD ONE FOURTH of the chocolate mixture into egg whites, then fold egg-white mixture into remaining chocolate mixture and stir until completely incorporated. Divide among dessert dishes and chill for 1 hour before serving.